The present disclosure relates generally to a wearable system for, and a method of, electro-optically reading a symbol by image capture, and, more particularly, to capturing and processing an image of the symbol unobstructed by a user's finger that is generally pointed at the symbol.
Solid-state imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read targets, such as one- and two-dimensional bar code symbols, and/or non-symbols, such as documents, over a range of working distances relative to each reader. A typical imaging reader includes a housing having at least one light-transmissive window, and an imaging assembly that includes a solid-state imager or imaging sensor with an array of photocells or image sensors, which correspond to image elements or pixels in a field of view of the imager, and an imaging lens assembly for capturing return light scattered and/or reflected from the symbol being imaged over a range of working distances relative to the reader, and for projecting the return light onto the array to initiate capture of an image of each symbol. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, with global or rolling exposure shutters, and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the field of view.
In order to increase the amount of the return light captured by the array, for example, in dimly lit environments or for far-out symbols located relatively far from the window, the imaging reader generally also includes an illuminating light assembly for illuminating the symbol with illumination light over an illumination field for reflection and scattering from the symbol. In contrast to laser-based readers that direct a visible laser beam on the symbol, it is not always certain whether an imaging reader is pointed directly at the symbol and, as a result, the known imaging reader may also have an aiming light assembly for projecting an aiming light pattern or mark, such as a “crosshair” pattern, with aiming light from an aiming light source, e.g., an aiming laser or one or more light emitting diodes (LEDs), through aiming lenses on the symbol prior to imaging. The user aims the aiming pattern on the symbol to be imaged during an aiming mode prior to imaging and reading.
Although generally satisfactory for their intended purpose of reading symbols by image capture, the known handheld imaging readers have not proven to be altogether satisfactory, because, among other things, one of the user's hands is occupied with holding and aiming the reader, thereby preventing the user from using both his or her hands in such other operations as sorting, lifting, and carrying objects, such as packages, bearing the symbols. To perform such operations that are particularly desirable in the package delivery field, the user typically puts the reader down somewhere on some available support surface, thereby sometimes facilitating loss of the reader, or places the reader in a designated support, such as a cradle or a holster, thereby losing non-negligible time during the placement and retrieval of the reader. The use of the aiming light assembly not only consumes electrical energy and is costly, but its aiming light also may be bothersome to people in the vicinity of the reader.
To counter the handling drawback, the art has proposed not occupying one's hand by wearing a laser-based reader somewhere on a user's person, such as his or her head, arm, wrist, or finger, or on a pair of glasses, or on some article of clothing, such as a hat or helmet. To counter the energy wastage, cost and annoyance of the aiming light assembly employed in an imaging reader, the art has proposed having the user point his or her outstretched finger at the symbol. In the latter case, however, the outstretched finger sometimes overlies the symbol in the captured image and, as a result, the symbol cannot always be successfully read due to its at least partial obstruction and concealment by the outstretched finger. To make matters worse, the user has no advance knowledge that his or her outstretched finger is at least partly concealing the symbol and is compromising reader performance. This situation is, of course, unpredictable and unacceptable for a high performance reader.
Accordingly, there is a need to efficiently, rapidly and reliably image and read a symbol at which a user's finger is generally pointed, and to generally improve overall reading performance of wearable imaging readers.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and locations of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The system and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.